Powder/granular material feeder

ABSTRACT

A powder/granular material feeder is provided which can prevent bridges and rat holes, which makes a hopper less likely to vibrate, and which can be easily cleaned. 
     The powder/granular material feeder includes a hopper  1  for storing powder/granular material, and a screw conveyor  2  provided at the lower end of the hopper  1  for feeding powder/granular material in the hopper  1  to the next step, wherein the hopper  1  is a conical member having a downwardly decreasing diameter, and is made of a soft material, and wherein the powder/granular material feeder further includes rollers  3  and  4  in contact with the outer peripheral surface of the hopper  1 , a ring member  5  provided coaxially with the hopper  1  and supporting the rollers  3  and  4 , and a motor  8  for rotating the ring member  5 . With this arrangement, since the deflected positions of the hopper  1  caused by the contact with the rollers  3  and  4  continuously move in the circumferential direction when the ring member  5  rotates, the powder/granular material in the hopper ( 1 ) rotates. As a result, bridges and rat holes are less likely to form.

TECHNICAL FIELD

The present invention relates to a powder/granular material feeder forfeeding powder/granular material.

BACKGROUND ART

In the case of quantitatively feeding powder/granular material such asflour, corn starch, medicine, chemical fertilizer, resin pellets, cementor the like, a powder/granular material feeder is frequently used. Thepowder/granular material feeder includes a hopper for storingpowder/granular material, and a discharge apparatus connected to thelower end of the hopper, and is structured to feed the powder/granularmaterial in the hopper to the next step by the discharge apparatus.

In the powder/granular material feeder, since the feed rate of thepowder/granular material to the next step is equal to the decreasingamount of a total weight of the hopper and the discharge apparatus, itis possible to increase the feed precision of the powder/granularmaterial by installing a measuring device for detecting the total weightof the hopper and the discharge apparatus and controlling the dischargeapparatus based on a detection signal of the measuring device.

Control of the discharge apparatus carried out based on the detectionsignal of the measuring device includes a continuous operation controlin which the discharge apparatus is continuously operated whilecontrolling the transportation speed of the discharge apparatus in sucha manner that the feed rate of the powder/granular material per unittime becomes constant, and a batch operation control in which thedischarge apparatus is intermittently operated while controlling thetiming for switching actuation and stop of the discharge apparatus insuch a manner that the powder/granular material is fed by a fixed amount(batch).

The powder/granular material feeder mentioned above has a problem inthat if a bridge (arch shaped lump of the powder/granular material) or arat hole (cavity extending vertically through the powder/granularmaterial) forms in the powder/granular material within the hopper, thepowder/granular material within the hopper may be not be fed to the nextstep, even though powder/granular material remains in the hopper.

Accordingly, in order to prevent such bridges and rat holes, there havebeen proposed a powder/granular material feeder in which a vibrationgenerating apparatus is attached to the wall surface of the hopper(Patent Document 1), and a powder/granular material feeder including ahopper made of a soft material, and an oscillating plate providedoutside the hopper and oscillated by a link mechanism such that one andthe other ends of the oscillating plate alternately come into contactwith the wall surface of the hopper (Patent Document 2).

The powder/granular material feeder described in Patent Document 1vibrates the wall surface of the hopper by the vibration generatingapparatus, and prevents bridges and rat holes based on the vibrationtransmitted to the powder/granular material from the wall surface.Further, the powder/granular material feeder described in PatentDocument 2 makes the powder/granular material within the hopper flowtoward the center of the hopper based on deflection of the hopper whenthe oscillating plate comes into contact with the wall surface of thehopper, and prevents bridges and rat holes based on the flow.

However, in the powder/granular material feeder described in PatentDocument 1, since the hopper vibrates, a detection signal of themeasuring device for detecting the total weight of the hopper and thedischarge apparatus tends to be unstable if such a measuring device isused. Accordingly, it is difficult to stabilize the feed precision ofthe powder/granular material when controlling the discharge apparatusbased on the detection signal of the measuring device. In thepowder/granular material feeder described in Patent Document 2, sincethe hopper vibrates by a shock when the oscillating plate comes intocontact with the wall surface of the hopper, the detection signal of themeasuring device tends to be unstable.

Further, there has been known a powder/granular material feederstructured such that an agitating member is provided within a hopper,and the agitating member is rotated to prevent bridges and rat holes(Patent Document 3). Since the powder/granular material feeder directlyagitates the powder/granular material within the hopper and not throughthe wall surface of the hopper, the hopper is less likely to vibrate.Accordingly, in the case of installing the measuring device fordetecting the total weight of the hopper and the discharge apparatus,the detection signal of the measuring device tends to be stable.

However, in this powder/granular material feeder, there is a case thatpowder/granular material attached to the agitating member grows into alump when the agitating member rotates, and movement of thepowder/granular material from the hopper to the discharge apparatus isprevented due to the lump of the powder/granular material. Further, inthis powder/granular material feeder, the agitating member forms anobstacle when cleaning the interior of the hopper. Further, it isnecessary to clean the agitating member in addition to the hopper. Thisincreases the number of portions to be cleaned.

Patent Document 1: Japanese Unexamined Patent Publication No. 2004-51339(FIG. 3)

Patent Document 2: Japanese Unexamined Utility Model Publication No.58-45234

Patent Document 3: Japanese Unexamined Patent Publication No. 6-32458

DISCLOSURE OF THE INVENTION Object of the Invention

An object of the present invention is to provide a powder/granularmaterial feeder which can prevent bridges and rat holes, which makes ahopper less likely to vibrate, and which can be easily cleaned.

Means for Achieving the Object

In order to achieve this object, the powder/granular material feederaccording to the present invention includes a hopper which is a conicalmember having a downwardly decreasing diameter, and made of a softmaterial, and further comprises at least one roller in contact with theouter peripheral surface of the hopper, a ring member provided coaxiallywith the hopper and supporting the roller, and a motor for rotating thering member. Preferably, there are provided a plurality of the rollersarranged so as to be spaced from each other in the circumferentialdirection.

Further, the present invention further provides a powder/granularmaterial feeder which is further provided with a measuring device fordetecting the total weight of the hopper and the discharge apparatus,and a controller for controlling the discharge apparatus based on adetection signal of the measuring device.

EFFECTS OF THE INVENTION

In the powder/granular material feeder according to this invention, thehopper is radially inwardly deflected by contact of the hopper with theroller. When the ring member rotates, the deflected portion of thehopper continuously moves in the circumferential direction. At thistime, since the powder/granular material is the hopper is pushed by theinner peripheral surface of the hopper so as to flow in thecircumferential direction, and the powder/granular material in thehopper rotates as a whole due to this flow, bridges and rat hole areless likely to form.

Further, since the powder/granular material feeder prevents bridges andrat holes based on the continuous movement of the deflected position ofthe hopper, the hopper is less likely to vibrate.

Further, in the powder/granular material feeder, since there is noagitating member in the hopper, there is no problem that powder/granularmaterial attached to the agitating member grows into a lump, so that thepowder/granular material can be smoothly moved from the hopper to thedischarge apparatus.

Further, in the powder/granular material feeder, since there is noagitating member in the hopper, cleaning is easy.

Further, in the structure in which the plurality of the rollers areprovided so as to be spaced in the circumferential direction, since theforces in the radial direction acting on the hopper from the respectiverollers cancel each other, the center position of the hopper becomesstable, and it is possible to effectively prevent the vibration of thehopper.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a powder/granular material feederaccording to an embodiment of this invention.

FIG. 2 is a sectional view taken along line II-II of FIG. 1.

FIG. 3( a) is a perspective view of a portion of a ring member of thepowder/granular material feeder shown in FIG. 1; and FIG. 3( b) is aperspective view of a portion of a hopper and a screw conveyor of thepowder/granular material feeder shown in FIG. 1.

FIG. 4 is a perspective view showing a used state of the powder/granularmaterial feeder shown in FIG. 1.

DESCRIPTION OF REFERENCE NUMERALS

-   1 hopper-   2 screw conveyor-   3, 4 roller-   5 ring member-   8 motor-   15 measuring device-   16 controller

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a powder/granular material feeder according to anembodiment of this invention. This powder/granular material feeder has ahopper 1 for storing powder/granular material, and a screw conveyor 2provided at the lower end of the hopper 1, and feeds the powder/granularmaterial within the hopper 1 to the next step by the screw conveyor 2.

The hopper 1 is a conical member having a downwardly decreasingdiameter, and made of a soft material. As the soft material, forexample, a rubber material such as polyethylene rubber, neoprene rubber,or silicone rubber, or a thermoplastic elastomer can be used. Rollers 3and 4 are kept in contact with the outer peripheral surface of thehopper 1. The rollers 3 and 4 are attached to a ring member 5 made of ahard material (e.g., metal, or plastic) so as to be spaced in thecircumferential direction, and the hopper 1 is pressed and deflectedradially inwardly by the rollers 3 and 4 (see FIG. 2).

As shown in FIG. 2, the ring member 5 is rotatably supported by a guidemember 6, and is held at a coaxial position with the hopper 1. A ringgear 7 is coaxially fixed to the ring member 5. The ring gear 7 mesheswith a drive gear 9 connected to a motor 8. Thus, when the motor 8 isrotated, its rotation is transmitted to the ring member 5, and the ringmember 5 is rotated.

As shown in FIG. 1, the outer peripheral surface of the hopper 1 isformed into a cylindrical shape at its portion that is in contact withthe rollers 3 and 4 so that the rollers 3 and 4 smoothly roll when thering member 5 is rotated.

The screw conveyor 2 has a tubular casing 10 formed integrally with thehopper 1, a screw shaft 11 inserted through the casing 10, and a motor12 (see FIG. 3( b)) for rotating the screw shaft 11.

As shown in FIG. 3( b), the casing 10 communicates with the lower end ofthe hopper 1, and is structured such that when powder/granular materialis put in the hopper 1, the powder/granular material flows into thecasing 10 through the lower end of the hopper 1. The powder/granularmaterial flowing into the casing 10 moves within the casing 10 based onthe rotation of the screw shaft 11, passes through a metal sleeve 13fitted to an open end of the casing 10, and is discharged to the nextstep.

The hopper 1 and the screw conveyor 2 are supported by a pedestal 14.The pedestal 14 is mounted on a measuring device 15, so that the totalweight of the hopper 1 and the screw conveyor 2 is detected by themeasuring device 15. The measuring device 15 is connected to acontroller 16 (see FIG. 1) for controlling the screw conveyor 2, and isstructured such as to transmit a detection signal corresponding to thetotal weight of the hopper 1 and the screw conveyor 2 to the controller16.

The controller 16 controls the screw conveyor 2 based on the detectionsignal transmitted from the measuring device 15. The control of thescrew conveyor 2 may be a continuous operation control in which thescrew shaft 11 is continuously rotated while controlling the rotatingspeed thereof in such a manner that the feed amount of thepowder/granular material per unit time (that is, the decreasing amountof the total weight of the hopper 1 and the screw conveyor 2 per unittime) becomes constant, or a batch operation control in which the screwshaft 11 is intermittently rotated while controlling the timing forswitching on and off of the rotation of screw shaft 11 in such a mannerthat the powder/granular material is fed by a fixed amount (batch).

With this powder/granular material feeder, the screw conveyor 2 isactuated with ring member 5 rotating, thereby dischargingpowder/granular material in the hopper 1 to outside by means of thescrew conveyor 2, as shown in FIG. 4. At this time, since each of thedeflected positions of the hopper 1 due to contact with the rollers 3and 4 continuously moves in the circumferential direction as shown by achain line in FIG. 2, the powder/granular material in the hopper 1 ispushed by the inner peripheral surface of the hopper 1 so as to flow inthe circumferential direction, and due to this flow, the powder/granularmaterial in the hopper 1 rotates as a whole and flows like an eddycurrent. As a result, lumps are less likely to form in thepowder/granular material in the hopper 1, and bridges and rat holes areprevented. Further, since the powder/granular material in the hopper 1flows like an eddy current into the lower end of the hopper 1, thepowder/granular material smoothly moves from the hopper 1 into the screwconveyor 2.

Since the powder/granular material feeder prevents bridges and rat holesbased on the continuous movement of the deflected positions of thehopper 1, the hopper 1 is less likely to vibrate. Accordingly, themeasurement value of the measuring device 15 becomes stable, and it ispossible to feed powder/granular material at a high precision.

Further, since there are a plurality of the rollers 3 and 4 arranged soas to be spaced in the circumferential direction in the powder/granularmaterial feeder, the forces in the radially direction acting on thehopper 1 from the respective rollers 3 and 4 cancel each other.Accordingly, the center position of the hopper 1 becomes stable, and thehopper 1 is less likely to vibrate even when the ring member 5 isrotated at a high speed.

Further, since there is no agitating member in the hopper 1 of thepowder/granular material feeder, there is no problem thatpowder/granular material attached to the agitating member grows into alump, so that powder/granular material can be smoothly moved from thehopper 1 into the screw conveyor 2.

Further, since there is no agitating member in the hopper 1 of thepowder/granular material feeder, the cleaning work is easily carriedout.

Further, it is not necessary to provide a link mechanism and the numberof parts is small, in the powder/granular material feeder, compared tothe powder/granular material feeder including the oscillating plateprovided outside the hopper and oscillated by the link mechanism toprevent bridges and rat holes. Accordingly, a low cost is achieved.

In the embodiment mentioned above, the casing 10 is formed integrallywith the hopper 1. But the casing 10 may be made of metal and beindependent from the hopper 1, and the casing 10 may be fixed to thehopper 1. In this case, the casing 10 may be fixed, for example, byforming a flange on the outer periphery of the hopper 1 at its lowerend, and fastening the flange and the casing 10 by bolts and nuts.

Further, in the embodiment mentioned above, two rollers 3 and 4 areattached to the ring member 5. But three or more rollers coming intocontact with the outer periphery of the hopper 1 may be attached so asto be spaced in the circumferential direction.

In the embodiment mentioned above, the screw conveyor 2 is employed asthe discharge apparatus connected to the lower end of the hopper 1 inorder to improve the feed precision of the powder/granular material. Butinstead of the screw conveyor 2, the discharge apparatus connected tothe lower end of the hopper 1 may be a belt conveyor or a rotary valve(valve comprising a horizontal cylindrical casing and an impeller andadapted to deliver powder/granular material on the upper side of theimpeller to the lower side thereof by rotating the impeller).

1-3. (canceled)
 4. A bulk material feeder comprising: a hopper (1) forreserving a bulk material; a discharge apparatus (2) continuouslyprovided in a lower end of the hopper (1); and the discharge apparatus(2) for feeding the bulk material within the hopper (1) to the nextstep, wherein the hopper (1) is formed into a downwardly diameterreduced conical shape, the hopper (1) is formed by a soft material, acylindrical outer peripheral surface around an axis of the hopper (1) isformed in an outer periphery of a portion having a conical innerperipheral surface of the hopper (1), rollers (3, 4) which are inparallel to the axis of the hopper (1) are brought into contact with theouter peripheral surface, the rollers (3, 4) are attached to a ringmember (5) which is provided coaxially with the hopper (1), and a motor(8) for rotationally driving the ring member (5) is provided.
 5. Thebulk material feeder according to claim 4, wherein the rollers (3, 4)are plurally provided so as to be spaced in a peripheral direction. 6.The bulk material feeder according to claim 5, further comprising ameasuring device (15) for detecting a total weight of the hopper (1) andthe discharge apparatus (2), and a controller (16) for controlling thedischarge apparatus (2) based on a detection signal of the measuringdevice (15).
 7. The bulk material feeder according to claim 4, furthercomprising a measuring device (15) for detecting a total weight of thehopper (1) and the discharge apparatus (2), and a controller (16) forcontrolling the discharge apparatus (2) based on a detection signal ofthe measuring device (15).